这个语句总是报错：Arithmetic overflow error converting varchar to data type numeric.

[feihongtao]

declare @li_days decimal(4,0),
@table_name char(12),
@user_code char(9)
EXEC('update '+@table_name+'
set gz_sbxz=(case
when salary_type=''C'' then cast((low_salary+gz_zgjt+gz_jsjt+gz_zwjt+gz_tzx)*day_number as decimal(4,0))
when salary_type=''B'' then cast((low_salary+gz_zgjt+gz_jsjt+gz_zwjt+gz_tzx) as decimal(4,0))
else
cast((low_salary+gz_zgjt+gz_jsjt+gz_zwjt+gz_tzx)*day_number/'''+@li_days+''' as decimal(4,0))
end)
from set_right_dept_dbf
where set_right_dept_dbf.dept_code='+@table_name+'.dept_code and
set_right_dept_dbf.if_enabled=''T'' and
set_right_dept_dbf.work_code='''+@user_code+''' ')

[feihongtao]

问题是出在这里：'''+@li_days+'''
如果我换成'+@li_days+'，还是报同样的错误：
Arithmetic overflow error converting varchar to data type numeric.

[feihongtao]

换成''+@li_days+''后，输出的是下面的结果，@li_days根本没接收传进去的参数。
update salary200704
set gz_sbxz=(case
when salary_type='C' then cast((low_salary+gz_zgjt+gz_jsjt+gz_zwjt+gz_tzx)*day_number as decimal(4,0))
when salary_type='B' then cast((low_salary+gz_zgjt+gz_jsjt+gz_zwjt+gz_tzx) as decimal(4,0))
else
cast((low_salary+gz_zgjt+gz_jsjt+gz_zwjt+gz_tzx)*day_number/'+@li_days+' as decimal(4,0))
end)
from set_right_dept_dbf
where set_right_dept_dbf.dept_code=salary200704.dept_code and
set_right_dept_dbf.if_enabled='T' and
set_right_dept_dbf.work_code='200473552'